Expert Testimony

An expert witness, particularly in common law countries such as the United Kingdom, Australia, and the United States, is a person whose opinion by virtue of education, training, certification, skills or experience, is accepted by the judge as an expert. The judge may consider the witness's specialized (scientific, technical or other) opinion about evidence or about facts before the court within the expert's area of expertise, to be referred to as an "expert opinion". Expert witnesses may also deliver "expert evidence" within the area of their expertise. Their testimony may be rebutted by testimony from other experts or by other evidence or facts.

History

The forensic expert practice is an ancient profession. For example, in ancient Babylonia, midwives were used as experts in determining pregnancy, virginity and female fertility. Similarly, the Roman Empire recognized midwives, handwriting experts and land surveyors as legal experts. The codified use of expert witnesses and the admissibility of their testimony and scientific evidence has developed significantly in the Western court system over the last 250 years. The concept of allowing an expert witness to testify in a court setting and provide opinionated evidence on the facts of other witnesses was first introduced by Lord Mansfield in the case of ''Folkes v. Chadd'' in 1782. In this particular case, the court was hearing litigation regarding the silting of Wells Harbor in Norfolk and allowed leading civil engineer, John Smeaton, to provide scientific rationale behind the proposed legislation. The decision by the English Court to allow for an expert to provide contextual background and detail on a case is often cited as the root of modern rules on expert testimony.

Role

Expert witnesses are called upon in the court system to serve as an objective party to the lawsuit and never function as an advocate for one side or the other. Expert witnesses are present in litigation to explain complicated scientific issues, not to influence the jury or judge with fervor. The main responsibilities of expert witnesses are to evaluate potential problems, defects, deficiencies, or errors only when able to fully appreciate a process or system.Cohen, Kenneth (2015-08-05). ''Expert Witnessing and Scientific Testimony : A Guidebook, Second Edition''. Chapman and Hall/CRC. . Expert witnesses are obligated to study the processes prior to making a survey or postpone the assignment prior to potentially missing the target due to lack of specific condition understanding. They are called to testify under the assumption that all the preparation required for a competent evaluation of the process has been made.

Typically, experts are relied on for opinions on severity of injury, degree of sanity, cause of failure in a machine or other device, loss of earnings and associated benefits, care costs, and the like. In an intellectual property case an expert may be shown two music scores, book texts, or circuit boards and asked to ascertain their degree of similarity. In the majority of cases, the expert's personal relation to the defendant is considered and usually adjudged to be irrelevant.

The tribunal itself, or the judge, can in some systems call upon experts to technically evaluate a certain fact or action, in order to provide the court with a complete knowledge on the fact/action it is judging. The expertise has the legal value of an acquisition of data. The results of these experts are then compared to those by the experts of the parties.

The expert has a great responsibility, and especially in penal trials, and perjury by an expert is a severely punished crime in most countries. The use of expert witnesses is sometimes criticized in the United States because in civil trials, they are often used by both sides to advocate differing positions, and it is left up to a jury to decide which expert witness to believe. Although experts are legally prohibited from expressing their opinion of submitted evidence until after they are hired, sometimes a party can surmise beforehand, because of reputation or prior cases, that the testimony will be favorable regardless of any basis in the submitted data; such experts are commonly disparaged as "hired guns."

Qualifications

An expert witness at the time of trial is qualified by the court and must be re-qualified each time that person comes to trial for the offering of opinions. The qualification is given by each trial judge and takes place regardless of prior appearances by a particular expert witness. Expert witnesses are those whom the court has deemed qualified to speak on a topic to provide background to anyone on a lay jury.

Duties in United States courts

In high stakes cases multiple experts, in multiple topics, are often retained by each party. Although it is still relatively rare, the court itself may also retain its own independent expert. In all cases, fees paid to an expert may not be contingent on the outcome of the case.

Expert evidence is often the most important component of many civil and criminal cases today. Fingerprint examination, blood analysis, DNA fingerprinting, and forensic firearm examination are common kinds of expert evidence heard in serious criminal cases. In civil cases, the work of accident analysis, forensic engineers, and forensic accountants is usually important, the latter to assess damages and costs in long and complex cases. Intellectual property and medical negligence cases are typical examples.

Electronic evidence has also entered the courtroom as critical forensic evidence. Audio and video evidence must be authenticated by both parties in any litigation by a forensic expert who is also an expert witness who assists the court in understanding details about that electronic evidence.

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